Signal transmission method and signal transmission apparatus

Abstract

A high-quality transmission apparatus for a 1-bit digital signal. The 1-bit digital signal is transmitted via a phase modulator arranged upstream of a transmission route and demodulated by a phase demodulator arranged downstream of the transmission route for suppressing the jitter caused by power source variations and radiation noise during transmission.

What is claimed is: 
     
       1. A signal transmission apparatus in which a 1-bit digital signal output from a ΣΔ modulator is transmitted over a transmission system, the apparatus comprising: phase modulation means for phase-modulating the 1-bit digital signal output from the ΣΔ modulator and generating a phase-modulated 1-bit signal for transmission over the transmission system;   means connected to the phase modulation means for providing a clock signal to the phase modulation means to establish a pre-set transmission rate equal to a transmission rate of the 1-bit digital signal output from the ΣΔ modulator; and   phase demodulation means for demodulating the phase-modulated 1-bit signal output from the transmission system,   wherein the 1-bit digital signal transmitted over the transmission system is prevented from being deteriorated due to power source variations and radiation noise.   
     
     
       2. The signal transmission apparatus as claimed in claim 1, wherein the phase modulation means outputs a positive-phase output and a reverse-phase output of the 1-bit digital signal based on the 1-bit digital signal output from the ΣΔ modulator, the positive-phase output and the reverse-phase output of the 1-bit digital signal being alternately output at a rate twice the pre-set transmission rate for generating the phase-modulated signal. 
     
     
       3. The signal transmission apparatus as claimed in claim 2, wherein the phase demodulation means demodulates the phase-modulated signal transmitted over the transmission system based on the pre-set transmission rate established by the clock signal. 
     
     
       4. The signal transmission apparatus as claimed in claim 3, wherein the pre-set transmission rate of the phase demodulation means is generated based on the clock signal extracted from the phase-modulated signal transmitted over the transmission system. 
     
     
       5. The signal transmission apparatus as claimed in claim 1, wherein the phase demodulation means demodulates a positive-phase output and a reverse-phase output of the 1-bit digital signal from the phase-modulated signal transmitted over the transmission system. 
     
     
       6. The signal transmission apparatus as claimed in claim 1, wherein the phase demodulation means demodulates the phase-modulated signal using an analog FIR filter. 
     
     
       7. A signal transmission method in which a 1-bit digital signal output from a ΣΔ modulator is transmitted over a transmission system, the method comprising the steps of: phase modulating the 1-bit digital signal output from the ΣΔ modulator based on a clock signal which establishes a pre-set transmission rate equal to a transmission rate of the 1-bit digital signal output from the ΣΔ modulator;   transmitting the phase-modulated 1-bit signal obtained by phase modulation of the 1-bit digital signal output from the ΣΔ modulator over the transmission system; and   demodulating the phase-modulated 1-bit signal output from the transmission system based on the pre-set transmission rate in order to prevent deterioration of the transmitted 1-bit digital signal due to at least one of power source variations and radiation noise.   
     
     
       8. A signal transmission apparatus in which a 1-bit digital signal output from a ΣΔ modulator is transmitted over a transmission system, the apparatus comprising: means providing a clock signal for establishing a pre-set transmission rate;   a first D-latch for latching the 1-bit digital signal output from the ΣΔ modulator and generating a phase-modulated signal in response to the clock signal; and   a second D-latch for latching the phase-modulated signal transmitted over the transmission system and generating the 1-bit digital signal in response to a rising edge of the clock signal,   wherein pre-set transmission rate set by the clock signal is equal to a transmission rate of the 1-bit digital signal output from the ΣΔ modulator.   
     
     
       9. A signal transmission apparatus in which a 1-bit digital signal output from a ΣΔ modulator is transmitted over a transmission system, the apparatus comprising: phase modulation means for phase-modulating the 1-bit digital signal output from the ΣΔ modulator and generating a phase-modulated 1-bit signal which is transmitted over the transmission system;   means connected to the phase modulation means for providing a clock signal to the phase modulation means to establish a pre-set transmission rate equal to a transmission rate of the 1-bit digital signal output from the ΣΔ modulator; and   phase demodulation means for demodulating the phase-modulated 1-bit signal transmitted over the transmission system, the phase demodulation means including clock auto-extraction means for extracting clock components from the phase-modulated 1-bit signal for locking a phase-locked-loop for bit synchronization,   wherein the 1-bit digital signal transmitted over the transmission system is prevented from being deteriorated due to power source variations and radiation noise.